Small RAR archive named only for a Z87-PLUS board, which matches an Asus desktop motherboard on the Intel Z87 chipset, though the name does not state its contents. At this size it most likely holds a boardview or similar service file rather than a full BIOS. Open it and identify the format before use; boardview files help locate components and trace nets when diagnosing shorts on VRM or chipset rails. Check the PCB revision printed on the board against any revision given inside the archive.
The button opens the matching file on RM Schematics, or a source page if it is not catalogued there yet. The original attachment is from @boardview. Enginerys does not host this file.
How to open a .rar file
Compressed archive — the usual wrapper for a schematic + boardview pair or a BIOS + EC set.